IoT-blockchain applications have advantages of managing massive IoT devices, achieving advanced data security, and data credibility. However, there are still some challenges when deploying IoT applications on blockchain systems due to limited storage, power, and computing capability of IoT devices. Applying current consensus protocols to IoT applications may be vulnerable to Sybil node attacks or suffer from high-computational cost and low scalability. In this paper, we propose G-PBFT (Geographic-PBFT), a new location-based and scalable consensus protocol designed for IoT-blockchain applications. The principle of G-PBFT is based on the fact that most IoT-blockchain applications rely on fixed IoT devices for data collection and processing. Fixed IoT devices have more computational power than other mobile IoT devices, e.g., mobile phones and sensors, and are less likely to become malicious nodes. G-PBFT exploits geographic information of fixed IoT devices to reach consensus, thus avoiding Sybil attacks. In G-PBFT, we select those fixed, loyal, and capable nodes as endorsers, reducing the overhead for validating and recording transactions. As a result, G-PBFT achieves high consensus efficiency and low traffic intensity. Moreover, G-PBFT uses a new era switch mechanism to handle the dynamics of the IoT network. To evaluate our protocol, we conduct extensive experiments to compare the performance of G-PBFT against existing consensus protocol with over 200 participating nodes in a blockchain system. Experimental results demonstrate that G-PBFT significantly reduces consensus time, network overhead, and is scalable for IoT applications.
Abbas Yazdinejad, Gautam Srivastava, Reza M. Parizi, Ali Dehghantanha · 6 authors
Traditional Internet of Things (IoT) system architectures are centralized. Data from the devices are stored on the back-end, where they are processed and analyzed, and then reconnected to IoT devices. The scalability of centralized systems is very limited especially when an abundance of devices exist on an IoT network. Network security in IoT networks is another aspect at stake that could be compromised easily due to the unavailability of security in design mechanisms in most IoT networks. Blockchain technology is a distributed ledger without any intensive management that can store all transactions which leads to large amounts of data that increases over time. Large data amounts will be more pronounced with the increasing IoT devices and blockchain use cases involving IoT. IoT devices are for the most part constrained in both energy, storage, and computation, unlikely to be able to store all blockchain data. The current implementation of blockchain is not IoT friendly. Moreover, consensus on the blockchain using Proof of Work (PoW) is infeasible due to computational constraints. In this paper, we propose a Secure and Low latency Proof of Work (SLPoW) protocol. We also bring the computation of miners onto a Field-programmable gate array (FPGA) to improve the processing speeds of computation. We consider our resulting blockchain technology using SLPoW suitable for the evolving Green IoT setting.
Distributed networks have been widely studied in literature. However, the blockchain paradigm has inspired to revisit some of the results under a different point of view. In this paper, we analyze the "classic" spam protection problem applied to the IOTA Tangle, a distributed ledger technology which addresses Bitcoin's (monetary and energy) efficiency issues through the absence of mining pools. However, the lack of miners makes the network vulnerable to denial of service attacks. We propose an anti spam mechanism based on the solution of a cryptographic puzzle: When a node wants to generate a new transaction, it dynamically adapts the difficulty of the puzzle depending on its target throughput and on its reputation score. Specifically, the adaptive difficulty property guarantees that any node, even with low hashing power, can achieve similar throughput for a given reputation. In the paper, we prove this claim both analytically and through simulations, and we show that fairness between low- and high-power nodes is indeed reached.
The rising demand for wireless services can only be met if the available spectrum is shared effectively, and spectrum underutilization is avoided. This article examines how a DLT-based spectrum authorization system may be designed considering its protocol, data, and network operational layers. Decentralization, automation, and verifiable trust achieved by this system facilitate spectrum sharing and trading, catering to business objectives in addition to the influences from regulatory and technological developments. To this end, we elaborate on the technical feasibility, scalability, and business incentives for such a system to stimulate the multiple cross-industry stakeholders to use the radio spectrum more efficiently for 5G and beyond.
Low throughput has been the biggest obstacle of large-scale blockchain applications. During the past few years, researchers have proposed various schemes to improve the systems' throughput. However, due to the inherent inefficiency and defects of the Internet, especially in data broadcasting tasks, these efforts all rendered unsatisfactory. In this paper, we propose a novel blockchain protocol which utilizes the satellite broadcasting network instead of the traditional Internet for data broadcasting and consensus tasks. An automatic resumption mechanism is also proposed to solve the unique communication problems of satellite broadcasting. Simulation results show that the proposed algorithm has a lower communication cost and can greatly improve the throughput of the blockchain system. Theoretical estimation of a satellite broadcasting enabled blockchain system's throughput is 6,000,000 TPS with a 20 gbps satellite bandwidth.
Ever since the concept of parallel processing and remote computation became feasible, Cloud computing is at its highest peak in its popularity. Although cloud computing is effective and feasible in its usage, using the cloud for frequent operations may not be the be the most optimal solution. Hence the concept of FOG proves to be more optimal and efficient. In this paper, we propose a solution by improving the FOG computing concept of decentralization by implementing a secure distributed files system utilizing the IPFS and the Ethereum Blockchain technology. Our proposed system has proved to be efficient by successfully distributing the data in a Raspberry Pi network. The outcome of this work will assist FOG architects in implementing this system in their infrastructure and also prove to be effective for IoT developers in implementing a Raspberry Pi decentralized network while providing more security to the data.
While direct allocation of spectrum and evolved medium access protocols\nprovide a base for ubiquitous wireless connectivity, the existing TCP/IP and\nOSI models were designed for wired networks and do not address open\ninterconnection of air interfaces. Without an interconnection model for the air\ninterface, existing network designs continue to tie wireless medium access to\nthat of the backhaul provider for ownership of access and identity trust,\nresulting in limitations on functionality and coverage. In this paper, we\npropose a novel solution to access ownership and identity trust by extending\nthe TCP network standard, under a new model we propose, named TCP-Air which\nintegrates distributed ledger technologies directly at the air interface.\nFurther, we present two use cases of the TCP-Air model, demonstrating\napplications not feasible under existing permissioned-access network designs.\n
This paper combines additive homomorphic encryption and consortium blockchain technology to provide privacy and trust. Additionally, a dynamic energy pricing model is formulated based on the demand response ratio (DRR) of the load demand of prosumers to address fixed energy pricing problems. The proposed dynamic pricing model includes demurrage fees, which is a monetary penalty imposed on a prosumer, if it failed to deliver energy within the agreed duration. Furthermore, this paper also designs and analyzes a threat model of the proposed system. Experimental evaluations show the effectiveness of the proposed model with regards to low transaction cost, the minimum execution time for block creation, the privacy of prosumers and dispute resolution of demurrage fees. Moreover, the proposed scheme reduces the average system overhead cost up to 66.67% as compared to 33.43% for an existing scheme. Additionally, the proposed blockchain proof-of-authority consensus average hash power is minimized up to 82.75% as compared to 60.34% for proof-of-stake and 56.89% for proof-of-work consensus mechanisms.
Marten Sigwart, Philipp Frauenthaler, Christof Spanring, Michael Sober · 5 authors
Today, several solutions for cross-blockchain asset transfers exist. However, these solutions are either tailored to specific assets or neglect finality guarantees that prevent assets from getting lost in transit. In this paper, we present a cross-blockchain asset transfer protocol that supports arbitrary assets and adheres to finality requirements. The ability to freely transfer assets between blockchains may increase transaction throughput and provide developers with more flexibility by allowing them to design digital assets that leverage the capacities and capabilities of multiple blockchains.
Mehrdad Salimitari, Mainak Chatterjee, Yaser P. Fallah
The success of blockchain as the underlying technology for cryptocurrencies has opened up possibilities for its use in other application domains as well. The main advantages of blockchain for its potential use in other areas are its inherent security mechanisms and immunity to data manipulation attacks. A blockchain relies on a consensus method for agreeing on any new data. Most of the consensus methods which are currently used for the blockchain of different cryptocurrencies require high computational power and thus are not suitable for resource-constrained systems. In this article, we survey the various blockchain-based consensus methods that are applicable to resource-constrained IoT devices and networks. In a typical IoT network, there exist several devices with limited computational and communication capabilities. Most often, these devices cannot perform intensive computations and are starved for bandwidth. Therefore, we discuss the possible measures that can be taken to reduce the computational power and convergence time for the underlying consensus methods. We also talk about some of the alternatives to the public blockchain, such as private blockchain and tangle, along with their potential adoption for IoT networks. Furthermore, we review the existing consensus methods that have been implemented and explore the possibility of utilizing them to realize a blockchainbased IoT network. Some of the open research challenges including AI-enabled blockchains are also put forward.
Xi Tong Lee, Arijit Khan, Sourav Sen Gupta, Yu Hann Ong · 5 authors
Blockchains are increasingly becoming popular due to the prevalence of cryptocurrencies and decentralized applications. Ethereum is a distributed public blockchain network that focuses on running code (smart contracts) for decentralized applications. More simply, it is a platform for sharing information in a global state that cannot be manipulated or changed. Ethereum blockchain introduces a novel ecosystem of human users and autonomous agents (smart contracts). In this network, we are interested in all possible interactions: user-to-user, user-to-contract, contract-to-user, and contract-to-contract. This requires us to construct interaction networks from the entire Ethereum blockchain data, where vertices are accounts (users, contracts) and arcs denote interactions. Our analyses on the networks reveal new insights by combining information from the four networks. We perform an in-depth study of these networks based on several graph properties consisting of both local and global properties, discuss their similarities and differences with social networks and the Web, draw interesting conclusions, and highlight important, future research directions.
The Binary Vector Clock is a simple, yet space-efficient algorithm for generating a partial order of transactions in account-based blockchain systems. The Binary Vector Clock solves the problem of order dependency in systems such as Ethereum, caused by the total order of transactions that come from the same address holder. The proposed algorithm has the same security as using regular transaction nonces, requires very little overhead, and can potentially result in a significant increase in throughput for systems like Ethereum.
Lam Duc Nguyen, Israel Leyva‐Mayorga, Petar Popovski
Distributed Ledger Technologies (DLTs) are playing a major role in building security and trust in Internet of Things (IoT) systems. However, IoT deployments with a large number of devices, such as in environment monitoring applications, generate and send massive amounts of data. This would generate vast number of transactions that must be processed within the distributed ledger. In this work, we first demonstrate that the Proof of Work (PoW) blockchain fails to scale in a sizable IoT connectivity infrastructure. To solve this problem, we present a lightweight distributed ledger scheme to integrate PoW blockchain into IoT. In our scheme, we classify transactions into two types: 1) global transactions, which must be processed by global blockchain nodes and 2) local transactions, which can be processed locally by entities called witnesses. Performance evaluation demonstrates that our proposed scheme improves the scalability of integrated blockchain and IoT monitoring systems by processing a fraction of the transactions, inversely proportional to the number of witnesses, locally. Hence, reducing the number of global transactions.
Lam Duc Nguyen, Anders E. Kalør, Israel Leyva‐Mayorga, Petar Popovski
The data collected from Internet of Things (IoT) devices on various emissions or pollution, can have a significant economic value for the stakeholders. This makes it prone to abuse or tampering and brings forward the need to integrate IoT with a Distributed Ledger Technology (DLT) to collect, store, and protect the IoT data. However, DLT brings an additional overhead to the frugal IoT connectivity and symmetrizes the IoT traffic, thus changing the usual assumption that IoT is uplink-oriented. We have implemented a platform that integrates DLTs with a monitoring system based on narrowband IoT (NB-IoT). We evaluate the performance and discuss the tradeoffs in two use cases: data authorization and real-time monitoring.
Blockchain systems have received much attention and promise to revolutionize many services. Yet, despite their popularity, current blockchain systems exist in isolation, that is, they cannot share information. While interoperability is crucial for blockchain to reach widespread adoption, it is difficult to achieve due to differences among existing blockchain technologies. This paper presents a technique to allow blockchain interoperability. The core idea is to provide a primitive operation to developers so that contracts and objects can switch from one blockchain to another, without breaking consistency and violating key blockchain properties. To validate our ideas, we implemented our protocol in two popular blockchain clients that use the Ethereum virtual machine. We discuss how to build applications using the proposed protocol and show examples of applications based on real use cases that can move across blockchains. To analyze the system performance we use a real trace from one of the most popular Ethereum applications and replay it in a multi-blockchain environment.
B. Saravana Balaji, P. Raja, Anand Nayyar, Sanjeevikumar Padmanaban · 5 authors
Blockchain technology is increasingly used worldwide to enhance the performance and profit of any environment through its defining characteristics, such as security, auditability, immutability, and inconspicuousness. Owing to these characteristics, the blockchain can be used in various non-financial operations of some domains, such as the Internet of Things (IoT) and distributed computing. However, implementing blockchain technology in IoT is not always a feasible solution because blockchain deployment is costly, it has limited extensibility and provides irregular bandwidth and latency. In this regard, a simple size extensible (SSE) blockchain has been proposed to provide an optimal solution for IoT environments by satisfying the needs of the IoT environment as well as ensuring end-to-end security. The implementation of the proposed blockchain develops an overlay network to obtain a distributed environment where the blockchain is handled by the resources present therein. Two novel algorithms were introduced into the proposed system to minimize the irregularity and latency on one hand, and to maximize the throughput of the system on the other. The shared-time depending agreement algorithm (STD) minimizes the irregularity in the extraction operation and latency. The other, the shared throughput administration algorithm (STA) justifies the overall collection of the transmission load in the network and maintains the performance of the blockchain. The proposed system was applied to smart home IoT appliances to test the performance of the proposed system. The experimental results show that the proposed blockchain system minimizes nearly 70% of the data irregularity, latency, and furthermore, 30% of the blockchain extensibility is maximized as compared to the existing systems.
Badr Eddine Sabir, Mohamed Youssfi, Omar Bouattane, Hakim Allali
The Internet of Things (IoT) is becoming an indispensable part of the actual Internet and continues to extend deeper into the daily lives of people, offering distributed and critical services. Mobile agents are widely used in the context of IoT and due to the possibility of transmitting their execution status from one device to another in an IoT network, they offer many advantages such as reducing network load, encapsulating protocols, exceeding network latency, etc. Also, Blockchain Technology is growing rapidly allowing for the addition of an approved security layer in many areas. Security issues related to mobile agent migration can be resolved with the use of Blockchain. This paper aims to demonstrate how Blockchain Technology can be used to secure mobile agents in the context of the IoT using Ethereum and a Smart Contract. The transactions within the Blockchain are used to detect the malevolent mobile agents that could infiltrate the IoT systems. The proposed model aims to provide a secure migration of mobile agents to ensure security and protect the IoT applications against malevolent agents. The case of a smart home with multiple applications is applied to verify the proposed solution. The model presented in this paper could be extended to a wider selection of IoT systems outside of the smart home.
Abstract The inability to scale is one of the most concerning problems looming in blockchain systems, where every node has to store all contents of the ledger database locally, leading to centralization and higher operation costs. In this paper, we propose a model named virtual block group (VBG), which aims at addressing the node storage scalability problem. Adopting the VBG model, each node only needs to store part of block data and saves the VBG storage index to distributed hash table by taking block data as a resource, thus improving the query efficiency of block data. With the incentive mechanism of block data storage, and the storage verification and audit mechanism of block data, the security and reliability of block data storage can be ensured. The analysis and calculation show that this model saves hard drive storage space of the node to a greater extent with a shorter time of requesting block data, in the premise of ensuring secure and reliable block data. Compared to other technologies such as sharding, our model does not change the consensus mechanism or the network topology and retains the reliability and security of the original blockchain system.
Li-e Wang, Yan Bai, Quan Jiang, Victor C. M. Leung · 6 authors
By facilitating multiple independent owners to jointly control a distributed network, blockchain can be used to solve the problem of device collaboration in complex networks (e.g., 5G, health care industries) through a distributed consensus mechanism. However, the state-of-the-art blockchain-based solutions cannot meet the demand of high transaction rate for those applications, due to the unavoidable data synchronization cost in decentralized systems. To address this issue, recent research splits blockchain nodes into multiple groups as parallel shardings to improve scalability at the cost of increased communication and storage per node. This paper proposes a fast and secure distributed blockchain protocol to reduce the traffic complexity while enhancing the transaction rates and the capability of fault-toleration. We introduce Proof-of-Behavior (PoB), a behavior-based incentive mechanism, for stimulating honest behavior and neutralizing malicious attacks. We design a blockchain protocol by integrating PoB with Raft, another classic consensus protocol with supervision, called Beh-Raft-Chain. Our approach replaces Practical Byzantine Fault Tolerance (PBFT) with Behavior-based Raft to lower the traffic complexity to O(n) and boost the capability of fault-toleration from n/4 to n/3, where n is the scale of blockchain. In our solution, we weigh all nodes based on their money and behaviors, and then set an adjustment parameter to increase the probability of candidate nodes being chosen beyond only a few nodes with the highest weight, in order to incentivize honest behavior in our mechanism. Our comparative experiments confirm Beh-Raft-Chain's theoretical low complexity and high fault-toleration properties.
Raheel Ahmed Memon, Jianping Li, Junaid Ahmed, Muhammad Irshad Nazeer · 6 authors
The Internet of Things (IoT) has been evolving for more than a decade. Technological advancements have increased its popularity, but concerns and risks related to IoT are growing considerably along with the increased number of connected devices. In 2013, a new cryptography-based infrastructure called blockchain emerged with the potential to replace the existing cloud-based infrastructure of IoT through decentralization. In this article, we provide a taxonomy of the challenges in the current IoT infrastructure, and a literature survey with a taxonomy of the issues to expect in the future of the IoT after adopting blockchain as an infrastructure. The two architectures are compared based on their strengths and weaknesses. Then a brief survey of ongoing key research activities in blockchain is presented, which will have considerable impact on overcoming the challenges encountered in the applicability of blockchain in IoT. Finally, considering the challenges and issues in both infrastructures and the latest research activities, we propose a high-level hybrid IoT approach that uses the cloud, edge/fog, and blockchain together to avoid the limitations of each infrastructure.
Martin Martinez, Arvin Hekmati, Bhaskar Krishnamachari, Seokgu Yun
We present a novel “Proof of Social Contact” approach to Sybil control that utilizes the analysis of digitally signed information about digitally signed pairwise encounters between mobile devices that are logged in a distributed ledger. To illustrate the approach, we show examples of analysis using binary classification techniques under two different adversary detection models, and evaluate them using a real-world mobile device encounter trace. We discuss a number of open problems and future directions that could be pursued by researchers in the field to realize and improve such a system and build on top of it.
Blockchain, as a promising solution to develop secure distributed ledgers, has drawn a huge attention over the last decade. By introducing a pseudonymous payment model with no central authority, blockchain marked the new generation of online payment systems, known as Cryptocurrencies. For most of the existing cryptocurrencies, scalability has become a challenging problem. When dealing with an ever increasing number of users, miners, and transactions, the technology is unable to scale and provide the same performance as centralised systems (e.g. centralised payment systems).Without addressing this fundamental scalability problem, such a promising technology may not be able to be adopted in mainstream. This paper provides an attempt to analyse the scalability of existing blockchain protocols and look at the major factors affecting scalability, namely throughput and latency. We also describe the HTNZ protocol, a new approach to improve the scalability of Satoshi Nakamoto's model [1], validated by experimental results. HTNZ introduces two new components, namely, sideBlock and helper. SideBlock has a slightly different structure of block and increases the number of transactions that can be processed per each interval.